The present invention relates to a new and improved construction of plate conveyor or moving walk, especially although not exclusively for transporting individuals, which is of the type comprising a series of plates or pallets arranged in tandem or succession in the direction of travel of the moving walk, the plates being connected with two mutually parallely extending, endless drive chains, there further being provided traveling rolls or rollers by means of which the moving walk can revolve at guide rails in one or a number of horizontal and/or inclined planes or portions. Since the plate conveyor or moving walk can be also used to convey loads, this term is obviously used in its broadest sense.
With such type prior art plate conveyors or moving walks the length of each plate, measured in the direction of travel of the conveyor belt, is a multiple of the division of the endless drive chain. The plates normally are arranged over the chains and are pivotably supported at one of their ends by prolonged pivot shafts or axles of the chain links. Traveling rolls are mounted at the prolonged pivot shafts, by means of which the conveyor belt revolves at guide rails. At their other end the plates are equipped with slots by means of which they are slidingly supported upon pivot shafts of the respective neighboring plate or at other prolonged or elongated pivot shafts of the chain links which likewise are equipped with traveling rolls. For safety reasons, and also to compensate the air gap or space needed at the connection locations of the plates, especially at the curved sections or portions of the path of travel, the ends of the plates are structured in a comb-like fashion, the tines or teeth of the comb of one plate engaging into the teeth gaps of the other plate.
These state-of-the-art plate conveyor belts or bands possess the advantage that they only need a reduced number of plates due to the relatively large plate length. Conversely, however, they have the drawback that they are unsuitable for paths of travel incorporating an inclined portion and horizontal access or entry portions, as such, for instance, is the case at installations which connect two superimposed landings or floors of a building. In order to prevent the formation of undesired kink or buckled locations at the connection locations of the plates, upon transition from a horizontal plane to an inclined plane at the load-carrying surfaces of the conveyor belt, it is imperative that such transition be accomplished at curves having a large radius. These kink or buckle locations must be avoided inasmuch as they endanger the safety of the user of the plate conveyor belt or moving-walk belt and also impair the user's comfort. When working with extremely long plates the radius of curvature can amount to as much as 20 meters. Therefore, it should be apparent that for a given useful path of travel of the conveyor belt the access parts of the total length of the equipment themselves must be appreciably enlarged.
A further drawback of such plate conveyor belt resides in the fact that the sprocket wheels arranged at the deflection locations of the drive chains must possess a diameter which coincides at least with the length of a plate. This, in turn, requires a relatively large height of the truss or frame for the related parts of the equipment. In the event there are used plates of extremely large length, then it is oftentimes necessary to provide at each deflection location a special device which retains the plates in horizontal position. This construction appreciably increases the costs of the installation.
If the employed plates have a large length, then, due to manufacturing inaccuracies or irregular wear, especially at the drive chains, there are formed alignment deviations i.e., misalignments. Equally, a slight inclination of the shafts carrying the plates can cause at the other end of the plates appreciable lateral and/or vertical displacements. The play which is usually present between the traveling plates and the stationary bannisters or guard rails, and whose permissible lateral and vertical size must comply with strict regulations or requirements, thereby can be abnormally enlarged or reduced in size or, in fact, totally eliminated. Consequently, it is not only extremely difficult to arrange the stationary bannisters over the load-carrying surfaces of the plates, but furthermore, if the arrangement of the bannisters is accomplished laterally of the plates, it is usually necessary to additionally provide expensive devices for the lateral guiding of the plates.
It logically follows that the use of short plates would enable avoiding these different drawbacks. In particular, there would then be possible an appreciable reduction in the size of the radius of curvature during the transition from a horizontal plane into an inclined plane. For a given length of the plates this reduction of the radius causes an appreciable enlargement of the sector angle. In the known installations, wherein the load-carrying surface of the plates is spaced at a relatively great distance from the hinge or pivot shafts of the drive chains, there would be produced an appreciable enlargement of the air gap or space between the plates with convex curves or a reduction or, in fact, a disappearance of such air gap in the case of concave curves. These differences in the width of the air gaps could be partially compensated by prolonging the comb teeth or teeth gaps, respectively, located at the plate ends. On the one hand, there would be increased the danger of rupture, and, on the other hand, at the location of the convex curves articles or even the fingers of the users, particularly children, could become caught in the intermediate spaces formed between the comb teeth and the gaps. It is because of this situation that the size of the requisite gap likewise has strict requirements imposed thereon.
Therefore, it would be advantageous to arrange the load-carrying surfaces of the plates in the same plane as, or in an approximately similar plane as the plane containing the hinge or pivot shafts of the drive chains. With the heretofore known plate conveyor bands this arrangement is practically impossible, since generally the shafts which pivotably support the plates also serve to mutually interconnect the drive chains.